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Artykuły w czasopismach na temat "Poly (methyl methacrylate) (PMMA) Thin Films"
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Yuwono, A. H., J. M. Xue, J. Wang, H. I. Elim, Wei Ji, Yuan Yuan Li i T. J. White. "Nonlinear Optical Behavior of Transparent Nanohybrids of Nanocrystalline TiO2 in Poly(methyl methacrylate) Prepared by In Situ Sol-Gel Polymerization Technique". Journal of Metastable and Nanocrystalline Materials 23 (styczeń 2005): 367–70. http://dx.doi.org/10.4028/www.scientific.net/jmnm.23.367.
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Nanohybrid thin films consisting of nanocrystalline TiO2 particles in poly(methyl methacrylate)(PMMA) were successfully synthesized by in-situ sol-gel and polymerization assisted by spin coating. Using titanium isoproproxide (Ti-iP), methyl methacrylate (MMA) and 3-(trimethoxysily)propyl methacrylate (MSMA) as the starting materials, nanohybrids containing up to 60% Ti-iP in PMMA were realized. The resulting nanohybrid thin films coated on quartz substrates are optically transparent and demonstrate nonlinear optical behaviour, where their nonlinear absorption increases with the loading of Ti-iP in PMMA, as confirmed by Z-scan measurements. Using pump-probe technique, these thin films are shown to exhibit an ultrafast relaxation time of ~1.5 picosecond.
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Liu, Chih-Ting, Chia-Chan Tsai, Chien-Wei Chu, Mu-Huan Chi, Pei-Yun Chung i Jiun-Tai Chen. "Dewetting of polymer thin films on modified curved surfaces: preparation of polymer nanoparticles with asymmetric shapes by anodic aluminum oxide templates". Soft Matter 14, nr 15 (2018): 2772–76. http://dx.doi.org/10.1039/c8sm00318a.
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Panapoy, M., P. Wannasut i Bussarin Ksapabutr. "Improvement of UV Protection Properties in Poly(Methyl Methacrylate) Sheet Coated by Titanium Dioxide/ Poly(Methyl Methacrylate) Hybrid Film". Advanced Materials Research 55-57 (sierpień 2008): 501–4. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.501.
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Titanium dioxide/poly(methyl methacrylate) (TiO2/PMMA) hybrid films with various amounts of TiO2 containing PMMA resin on PMMA sheets were produced by a tape casting method. TiO2 nanocrystals were prepared using electrospraying process at 400oC under high electric field of 3 kV/cm. The as-sprayed and annealed TiO2 powders were characterized by Raman spectroscopy, XRD, SEM and TEM. The UV absorption for both pristine PMMA sheet and TiO2/PMMA hybrid film on PMMA sheet was measured using UV-Vis spectroscopy. The as-sprayed and annealed TiO2 powders showed anatase preferred orientation. They have higher UV absorption in the range of wavelength between 230 and 370 nm than commercial anatase TiO2 nanopowders. Moreover, the visible light transmittances of anatase TiO2/PMMA hybrid films on PMMA sheets in the range of wavelength between 400 and 800 nm was comparable with those derived from pristine PMMA sheets. Therefore, the resulting hybrid films can block out the UV rays, but are transparent to visible light.
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B, Chandar Shekar, Sathisha S, Sulana Sundari, Sunnitha S i Sharmila C. "PREPARATION OF MESOSCOPIC STRUCTURE POLY METHYL METHACRYLATE THIN FILMS FOR AFM DATA STORAGE DEVICES." Kongunadu Research Journal 2, nr 1 (4.11.2019): 1–3. http://dx.doi.org/10.26524/krj54.
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Poly methyl methacrylate (PMMA) thin films were prepared by dip coating method. Benzene was used as a solvent to prepare PMMA thin films for the time periods ranging from 1 min. to 1 h. The thickness of the films deposited was measured by using an electronic thickness measuring instrument (Tesatronic-TTD-20). Fourier Transform Infrared spectrum was used to identify the above said films. X-ray diffraction spectra indicated the predominantly amorphous nature of the films. Surface morphology of the coated films studied by using scanning electron microscope (SEM) indicated the absence of any pits, cracks and pin holes in the surface. Both as grown and annealed films showed smooth and amorphous structures. The closer SEM inspection revealed the presence of self assembled mesoscopic cells. The mesoscopic structure PMMA thin films could be used as an AFM-based data storage which is promising alternative to conventional magnetic data storage because it offers great potential for considerable storage density improvements.
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Melo, Lis G. A., Adam P. Hitchcock, Darija Susac, Juergen Stumper i Viatcheslav Berejnov. "Effect of UV radiation damage in air on polymer film thickness, studied by soft X-ray spectromicroscopy". Physical Chemistry Chemical Physics 20, nr 24 (2018): 16625–40. http://dx.doi.org/10.1039/c7cp08621k.
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The thicknesses of thin films of polystyrene (PS), poly(methyl methacrylate) (PMMA), and perfluorosulfonic acid (PFSA) were measured by Ultraviolet Spectral Reflectance (UV-SR) and Scanning Transmission X-ray Microscopy (STXM).
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Mergen, Ömer Bahadır, Ertan Arda i Gülşen Akın Evingür. "Electrical, mechanical, and optical changes in MWCNT-doped PMMA composite films". Journal of Composite Materials 54, nr 18 (6.01.2020): 2449–59. http://dx.doi.org/10.1177/0021998319898507.
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In this study, we report the preparation of poly (methyl methacrylate)/multi-walled carbon nanotube (MWCNT) composite thin films by simple and efficient solution mixing and ultrasonic method and the electrical, optical, and mechanical characterizations. Scattered light intensity ( I sc), tensile modulus ( E), and surface conductivity ( σ) of these composites have increased with the addition of MWCNT into the composite. The observed behavior in electrical, optical, and mechanical properties of the poly (methyl methacrylate)/MWCNT composites was interpreted by site and classical percolation theory. The optical mechanical and electrical percolation thresholds of poly (methyl methacrylate)/MWCNT composites were determined as φ op = 3 wt%, φ m = 0 wt%, and φσ = 5 wt%, respectively. The optical ( t op), mechanical ( t m), and electrical ( t σ) critical exponents were calculated as 2.23, 0.43, and 0.11, respectively. Both the tensile modulus and tensile strength of poly (methyl methacrylate)/MWCNT composites were increased with increasing MWCNT content until it reaches to 10 wt%. However, above φ = 10 wt%, the mechanical properties of the composites were decreased due to the aggregation of MWCNTs, while the toughness does not show a significant change until φ = 10 wt% MWCNT content, whereas it was decreased above this value.
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Tippo, Tossapol, Chanchana Thanachayanont, Chabaiporn Junin, Seeroong Prichanont, Micheal Hietschold i Apinunt Thanachayanont. "Effect of Substrates on Preparation of Dissolved PMMA in DMF Solution Used as a Dielectric Layer in Otfts". Advanced Materials Research 802 (wrzesień 2013): 79–83. http://dx.doi.org/10.4028/www.scientific.net/amr.802.79.
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Dissolved Poly (methyl methacrylate) (PMMA) in Dimethylformamide solution was fabricated as thin films on different substrates, glass, poly (ethylene naphthalate) and Si wafer, using spin coating technique. The effect of different substrates on electrical performances of the PMMA films was investigated. For an acceptable organic thin-film transistor (OTFT) performance, uniform thickness with low defect density of the PMMA thin-films was required. A parallel plate capacitor structure was used to test electrical properties of the PMMA dielectric layers. Good dielectric properties were obtained on glass and PEN at film thicknesses of 95 nm. An optimal condition for the OTFT preparation was used to fabricate an OTFT with the PMMA dielectric layer on glass substrate. Measured results showed that the OTFT achieved a mobility of 0.16 cm2/V.s, a threshold voltage of -3.6 V, and on/off current ratio of 1×105.
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Zhao, Dong Lin, Hong Mei Chai, Yun Fang Liu i Zeng Min Shen. "Electrical Resistance Response of Carbon Nanotube / PMMA / PVAc Composite Sensors to Organic Vapours at Low Vapour Concentrations". Key Engineering Materials 334-335 (marzec 2007): 809–12. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.809.
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Thin films of poly(methyl methacrylate) (PMMA)，poly(vinyl acetate) (PVAc) and carbon nanotube composites were produced by different coating methods. The best way to produce the carbon nanotube / PMMA / PVAc composite film with conductive network is dispersing carbon nanotubes in PMMA and PVAc by ultrasonic and by solution casting. Electrical resistance responses of carbon nanotube / PMMA / PVAc composite sensors against various organic vapors at low concentrations are investigated. The experimental results indicate that the composites have high selectivity to various organic vapors at the same concentration. In addition, the electric resistance response of the composites against organic vapors takes place in step with their vapor adsorption procedure. Compatible blends of poly(methyl methacrylate) and poly(vinyl acetate) would be a good candidate to produce a series of electrically conducting carbon nanotubes composite film whose resistance is sensitive to the nature and concentration of an analyte in the vapor phase. The results indicate that the carbon nanotube / PMMA / PAVc composite film can be used as a novel organic vapor sensor to detect, quantify and discriminate various organic vapors.
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De Nisi, F., R. Francischello, A. Battisti, A. Panniello, E. Fanizza, M. Striccoli, X. Gu, N. L. C. Leung, B. Z. Tang i A. Pucci. "Red-emitting AIEgen for luminescent solar concentrators". Materials Chemistry Frontiers 1, nr 7 (2017): 1406–12. http://dx.doi.org/10.1039/c7qm00008a.
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This study reports for the first time the use of a red-emitting AIEgen, i.e. TPE-AC, for the realization of efficient luminescent solar concentrators (LSCs) based on poly(methyl methacrylate) (PMMA) and polycarbonate (PC) thin films (25 ± 5 μm).
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S. Ali, Ali, Karema M. Zaidan i Adnan Issa Al-Badran. "Preparation of Poly (methyl methacrylate) thin film Capacitors on ITO-glass substrate". Muthanna Journal of Pure Science 9, nr 2 (31.12.2022): 22–28. http://dx.doi.org/10.52113/2/09.02.2022/22-28.
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In electronic devices, some important materials having a high dielectric constant can be used. Polymer-ceramic composites have a high dielectric constant and are widely used for embedded capacitor applications. It is critical to use polymer poly methyl methacrylate (PMMA) as thin films capacitors for the gate dielectric in organic field-effect transistors (OFETs). In this work, thin films of polymer PMMA were prepared by using spin coating at different speeds (1500, 2000, 2500, 3000 and 3500 rpm) to control the film thickness and study the effect of the thickness on the dielectric properties. Thin film thickness was measured by using field emission scanning electron microscopy (FESEM) to take cross-section images. We found that the film thickness decreased with increased rotational speed from 27387 nm at 1500 rpm to 10600 nm at 3500 rpm. The values of the capacities were nearly stable with increasing frequencies when thickness equal to or larger than (14366 nm), but their increased with increased frequency at thickness (10600 nm), and the dielectric constant also decreases with increasing thin films thickness. The best result of capacitance value was at thickness 10600nm which equal to (5.753 nF) and dielectric constant equal to (3.511) which represents best value that can be used as dielectric gate for Organic Field Effect Transistor (OFET).
Rozprawy doktorskie na temat "Poly (methyl methacrylate) (PMMA) Thin Films"
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Kim, Ick Chan. "Experimental investigation of size effect on thermal conductivity for ultra-thin amorphous poly(methyl methacrylate) (PMMA) films". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1348.
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Maire, Helene C. "Characterization of cylindrical nano-domains in thin films of polystyrene-poly(methyl methacrylate) diblock copolymer studied via atomic force microscopy". Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1037.
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Cecci, Ricardo Rodrigo Ramos. "Síntese e caracterização de nanocompósitos de PMMA/NTC para aplicações em células fotovoltaicas orgânicas". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266636.
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Orientadores: Júlio Roberto Bartoli, Elizabeth Grillo FernandesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-22T08:51:19Z (GMT). No. of bitstreams: 1 Cecci_RicardoRodrigoRamos_M.pdf: 4182332 bytes, checksum: 4424cc557c439a1602d15a95921a2b25 (MD5) Previous issue date: 2013
Resumo: Nanotubos de carbono (NTCs) apresentam características interessantes para aplicações em eletrodos transparentes. Quando dispersos em escala nanométrica são transparentes ao espectro da luz visível e são capazes de conduzir eletricidade após atingirem percolação em matrizes poliméricas isolantes. Neste trabalho, é descrito o uso de nanotubos de carbono de camadas múltiplas (NTCMs) na produção de filmes poliméricos flexíveis transparentes e condutores como alternativa ao uso do óxido de índio dopado com estanho (ITO) em células solares orgânicas. Os nanotubos foram dispersos e purificados em solução aquosa de dodecil sulfato de sódio (SDS) pelos processos de sonicação e centrifugação, e a dispersão monitorada por espectroscopia UV-Vis e potencial ?. Os nanocompósitos foram produzidos via polimerização in situ do monômero metacrilato de metila (MMA) na presença de 0 a 1% p/p NTCs e os filmes depositados através da técnica de revestimento por rotação a alta velocidade (spin coating). A reação de polimerização foi acompanhada pela calorimetria exploratória diferencial (DSC). Verificou-se que na presença de NTCs, a taxa de conversão do monômero é acelerada. A cinética de degradação térmica foi avaliada pelo método de Broido utilizando a análise termogravimétrica (TGA). Foi observado que os NTCs aumentam a estabilidade térmica do PMMA, retardando a degradação por despolimerização. Estudos por espectroscopia FT-IR mostraram uma banda de absorção em 1601 cm-1, (C=C), a qual não é característica do PMMA, indicando que os NTCs participam da polimerização do PMMA. Para concentrações de até 1% p/p de NTCs, os filmes PMMA/NTC apresentaram excelentes propriedades ópticas. Ou seja, baixo coeficiente de absorção, na ordem de 103 cm-1, altos valores de gap óptico (Eopt), entre 3,2 e 4,14 eV, e alta transparência por todo espectro visível, entre 88 e 93%. Nas mesmas concentrações, foi observada uma diminuição substancial na resistividade elétrica dos filmes em 8 ordens de grandeza (de 1016 para 108 ?/quadrado), comparados ao filme de PMMA puro. Entretanto, a faixa de resistividade alcançada ainda é típica de materiais isolantes. Estudos de otimização poderiam originar filmes PMMA/NTC como uma alternativa promissora para ITO em OPVs
Abstract: Carbon nanotubes (CNTs) have interesting features for applications in transparent electrodes. When dispersed at the nanoscale, they become transparent within the visible range and are able to conduct electricity after reaching the percolation threshold in an insulating polymer matrix. In this work, the use of multi-walled carbon nanotubes (MWCNTs) is described for the production of flexible transparent conducting polymer films as an alternative to the use of indium-tin oxide (ITO) in organic solar cells. The nanotubes were dispersed and purified in an aqueous solution of sodium dodecyl sulfate (SDS) by the process of sonication and centrifugation, and the dispersion monitored by UV-Vis spectroscopy and ? potential. The nanocomposites were produced via in situ polymerization of the monomer methyl methacrylate (MMA) in the presence of 0 to 1 %wt. of CNTs. The films were deposited by the spin-coating technique. The polymerization reaction was monitored by differential scanning calorimetry (DSC). It was found that in the presence of CNTs, the conversion rate of the monomer is accelerated. The kinetics of thermal degradation was measured according to the Broido's method by using thermogravimetric analysis (TGA). It was observed that CNTs increase the thermal stability of PMMA, slowing degradation by depolymerization. FT-IR data showed an absorption band at 1601 cm-1 (C = C), which is not characteristic of PMMA, indicating that the CNTs takes place in the polymerization of PMMA. For concentrations up to 1wt% of CNTs, the PMMA/CNT films had excellent optical properties, i.e., a low absorption coefficient in the order of 103 cm-1, wide optical gap (Eopt) between 3.2 and 4.14 eV, and high transparency within the whole visible range, between 88 and 93%. In the same concentrations, the electrical resistivity of the films dropped by 8 orders of magnitude (from 1016 to 108 ?/sqr), compared to the pure PMMA film. Even though this electrical resistivity value is typical of insulating materials, further optimization studies could provide PMMA/CNT films as a promising alternative to ITO in OPV
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
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Hodgson, Mark Russell. "Co-operative degradation in thin films of poly(methyl methacrylate) and poly(ethylene terephthalate)". Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4334/.
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The interaction between thin films of polymethyi methacrylate and polyethylene terephthalate is reported. Studies of bulk PET/PMMA blends reveal that a direct ester exchange reaction occurs between the two polymers, and this information is used in the investigation of thin film interfaces between PET and PMMA. Discrete wavelength ellipsometry has been used to study the thermal decomposition of thin films of PMMA , and the crystallisation of thin films of PET. It is found that, below ~ 74.5 nm (6 x R(_g), the rate of degradation of PMMA (M(_N) ~ 44,000), increases with decreasing film thickness. For films < 100 nm , the rate of crystallisation of PET (M(_N) ~ 23,000), is found to decrease with decreasing film thickness. Using data obtained from neutron reflectometry, the equilibrium interfacial width between PET and dPMMA is measured. At an annealing temperature of 493K, the interface is broadened by crystalline roughness in the PET phase, and the maximum interfacial width is found to be ~7.7tmi. At 573K, despite extensive degradation of dPMMA, an equilibrium interfacial width of ~5nm is achieved. Capillary wave broadening and the effects of asymmetry are considered. A detailed analysis of Interfacial Marker Movements, reveals that there is an asymmetric broadening of the gold markers towards the PMMA side of the interface, indicative of a grafting reaction between PET and PMMA or a crosslinking reaction within the residual PMMA layer. The degradation of PET films, treated with acrylic based coating formulations has been studied by GPC, UV-vis spectrophotometry, and weight loss techniques. The rate of chain scission at 563K is seen to be dependant on the the concentration of tri methoxy methyl melamine (TMMM), the coating crosslinking agent.
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Gervasio, Michelle Rose. "Sub-micron Patterning of ZnO-PMMA Hybrid Films". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/86887.
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Sub-micron patterning is fundamental to the fabrication of numerous devices Traditional commercial manufacturing methods either lack the resolution needed to attain the appropriate size or are prohibitively expensive due to low throughput or the necessity of expensive equipment. Imprint lithography is a rapid, inexpensive alternative to making sub-micron features that can be tailored to work with a variety of materials. Imprint lithography, while traditionally used with pure polymers has been tailored to be used with nanoparticle-polymer hybrid films. This work has achieved high-fidelity pattern transfer onto polymer-nanoparticle hybrid films with feature sizes as small as 250 nm.
The polymer-nanoparticle hybrid was fabricated by creating a liquid suspension of functionalized ZnO nanoparticles and poly(methyl methacrylate) (PMMA) in a solvent. The ZnO particles were functionalized by adding nonanoic acid in order to facilitate the dispersion of the particles in a non-polar solvent. This suspension was spread onto substrate, imprinted with a patterned stamp, allowed to dry, and was demolded. The final result was features ranging from 250 nm to 1 μm in size with good fidelity as determined by the accuracy of the feature replication and the surface roughness of the overall sample. The effect of the ZnO content as well as the method of combining the suspension components on the feature fidelity was studied. In general, it was found that feature fidelity is acceptable up to a dry-film composition of 15 vol% ZnO and that feature sizes above 500 nm were more tolerant of higher solids loading.
The same imprint lithography method was also used to pattern a polymer-derived SiOC glass. The SiOC was shown to be have interesting shrinkage properties where the feature-level linear shrinkage was up to 5% more than that of the bulk. The features were
shown to be stable during pyrolysis up to 1000oC and stable at operating temperatures up to 1000oC.
A constant number Monte Carlo simulation was used to describe the suspension behavior to confirm the empirical results from the physical experiments. The effects of Van der Waals forces, steric stabilization, depletion flocculation, as well as the physical impediment of entangled polymer chains were considered. A similar agglomeration behavior was shown in the simulations compared to the physical experiments.
This thesis shows that polymer-nanoparticle hybrid films are a compatible material for imprint lithography using appropriate suspension parameters. This is very important for a variety of applications and devices. Using imprint lithography to make these devices makes them cheaper and more accessible to the commercial market and can make a large number of theoretical devices a reality.Ph. D.
Sub-micron patterning is an integral part of making many modern technologies such as memory storage devices or integrated circuits. As this technology becomes smaller and smaller, the limiting factor for making these devices has become the ability to manufacture effectively at the appropriate scale. Traditional commercial manufacturing methods lack the resolution needed to attain small enough features. Manufacturing methods that can make small enough features are often either extremely expensive or offer incomplete control of the feature morphology. Imprint lithography is a high-throughput, inexpensive alternative to making sub-micron features that can be tailored to work with a variety of materials. Imprint lithography is simple process in which a patterned stamp is pressed into a softened film of material in order to transfer the pattern of the stamp onto that material. Traditionally, imprint lithography works best with polymers and researchers have struggled to pattern nanoparticle-based materials. This work has achieved high-fidelity pattern transfer onto polymer-nanoparticle hybrid films with feature sizes on the same order as the polymer films found reported in literature. The polymer-nanoparticle hybrid was realized by creating a liquid suspension of functionalized ZnO nanoparticles and poly(methyl methacrylate) (PMMA) in a solvent. The ZnO particles were functionalized by adding nonanoic acid, allowing the normally polar particles to disperse in the non-polar solvent needed to dissolve the PMMA. This suspension was spread onto a glass substrate, imprinted with a patterned stamp, allowed to dry, and was demolded. The final result was the successful transfer of features ranging from 250 nm to 1 μm in size with good fidelity. The effect of the ZnO content as well as the method of combining the suspension components on the feature fidelity was studied. To help prove the broad applicability of this imprint method, it was adapted for use with polymer-derived ceramics. Additionally, a computer simulation was developed to help understand the behavior of the nanoparticle-polymer suspension during the imprint process.
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Manole, Claudiu Constantin. "MOCVD and electrochemical polymeric thin films : elaboration, characterization, properties ans applications". Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0165/document.
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Ce mémoire traite de deux types de polymères en films minces: le poly (méthacrylate de méthyle) (PMMA) et le polypyrrole (PPy). Ces films minces ont été déposés par voie sèche et par voie humide. La voie sèche consiste à faire croitre les films polymères par un procédé original de dépôt chimique en phase vapeur assisté par photons (Chemical Vapor Deposition, CVD). La croissance implique l'activation UV des espèces monomères dans la phase gazeuse. Les deux polymères PMMA et PPy ont été obtenus pour la première fois par ce procédé de photo-CVD. La caractérisation des propriétés a mis en évidence des applications possibles en microélectronique, micro-optique et les dispositifs générant de la chaleur. La voie humide mise en œuvre pour déposer des films minces de polymères et d’hybrides organiques/inorganiques est une méthode électrochimique. Des films de PPy (organique) et de TiO2 nanostructuré (inorganique) ont été obtenus et caractérisés par différentes techniques électrochimiques. Des aspects supplémentaires de la croissance de PPy ont été mis en évidence par la résonance des plasmons de surfaceThe thesis deals with two types of polymeric thin films: poly (methyl methacrylate) (PMMA) and polypyrrole (PPy). The thin films were grown by a dry and a wet route. The dry route involved the growth of the polymeric films by an original process of Chemical Vapor Deposition, namely Photo-CVD. The growth involves the UV activation of the monomer species in the gas phase. Both PMMA and PPy were obtained for the first time by this Photo-CVD. The characterization highlighted properties with possible applications in microelectronics, micro-optics and as heat generating devices. The wet route involved the growth of polymeric and hybrid organic/inorganic thin films by an electrochemical approach. Organic PPy and inorganic TiO2 nanostructures were obtained and characterized by various electrochemical techniques. The growth aspects of PPy were supplementary highlighted by the Surface Plasmon Resonance
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Perez, Paul. "Fabrication of 3D Microfluidic Devices by Thermal Bonding of Thin Poly(methyl methacrylate) Films". Thesis, 2012. http://hdl.handle.net/10754/237271.
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The use of thin-film techniques for the fabrication of microfluidic devices has gained attention over the last decade, particularly for three-dimensional channel structures.
The reasons for this include effective use of chip volume, mechanical flexibility, dead volume reduction, enhanced design capabilities, integration of passive elements, and scalability. Several fabrication techniques have been adapted for use on thin films: laser ablation and hot embossing are popular for channel fabrication, and lamination is widely used for channel enclosure. However, none of the previous studies have
been able to achieve a strong bond that is reliable under moderate positive pressures.
The present work aims to develop a thin-film process that provides design versatility, speed, channel profile homogeneity, and the reliability that others fail to achieve.
The three building blocks of the proposed baseline were fifty-micron poly(methyl
methacrylate) thin films as substrates, channel patterning by laser ablation, and device assembly by thermal-fusion bonding. Channel fabrication was characterized and tuned to produce the desired dimensions and surface roughness. Thermal bonding was performed using an adapted mechanical testing device and optimized to produce the maximum bonding strength without significant channel deformation. Bonding multilayered devices, incorporating conduction lines, and integrating various types of
membranes as passive elements demonstrated the versatility of the process. Finally, this baseline was used to fabricate a droplet generator and a DNA detection chip based on micro-bead agglomeration.
It was found that a combination of low laser power and scanning speed produced channel surfaces with better uniformity than those obtained with higher values. In addition, the implemented bonding technique provided the process with the most reliable
bond strength reported, so far, for thin-film microfluidics. Overall, the present work proved to be versatile, reliable, and fast, making it a good candidate to reproduce several on-chip functions. Future work includes implementing thick-substrate
bonding techniques to further improve the process and decrease energy requirements.
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Silva, Hernandez Carlos Ardenis A. "Molecular Dynamic Simulation of Thermo-Mechanical Properties of Ultra-Thin Poly(methyl methacrylate) Films". Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7676.
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The thermal conductivity of PMMA films with thicknesses from 5 to 50 nanometers and
layered over a treated silicon substrate is explored numerically by the application of the
reverse non-equilibrium molecular dynamics (NEMD) technique and the development of
a coarse-grained model for PMMA, which allows for the simulation time of hundreds of
nanoseconds required for the study of large polymer systems.
The results showed a constant average thermal conductivity of 0.135 W/m_K for
films thickness ranging from 15 to 50 nm, while films under 15 nm in thickness showed
a reduction of 30% in their conductivity. It was also observed that polymer samples with
a degree of polymerization equal to 25% of the entanglement length had 50% less
thermal conductivity than films made of longer chains. The temperature profiles through
the films thickness were as predicted by the Fourier equation of heat transfer.
The relative agreement between the thermal conductivity from experiments
(0.212 W/m_K for bulk PMMA) and the results from this investigation shows that with
the proper interpretation of results, the coarse-grained NEMD is a useful technique to
study transport coefficients in systems at larger nano scales.
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Huang, Ｈui-Fang, i 洪慧芳. "Dispersion, Aggregation and Segregation Behaviors of Zirconia Nanoaprticles within Poly(methyl methacrylate) Thin Films". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/11566801499322681806.
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碩士國立中央大學
化學工程與材料工程研究所
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In this work, I investigated organic-inorganic thin films of poly (methyl methacrylate) (PMMA) homopolymers of three molecular weights (MWs, Mn =17, 45 and 105 kg/mol) hybridized with zirconia nanoparticles (ZrO2 NPs). Prior to mixing with PMMA, the ZrO2 NPs were surface-modified by grafting a layer of various carboxylic acids (methacrylic acid, butyric acid and linoleic acid). For brevity, the surface-modified ZrO2 NPs were designated as MA-ZrO2, BA-ZrO2 and LOA-ZrO2. In the following context, I systematically studied the dispersion, aggregation and segregation behaviors of surface-modified ZrO2 NPs within the PMMA thin films. The dispersion, aggregation and segregation behaviors of carboxylic acid-grafted ZrO2 NPs within PMMA homopolymers depend on the enthalpic effect. According to the solubility parameters, I proposed that the MA or BA dispersants are miscible with PMMA whereas LOA is immiscible with PMMA. The former cases revealed the dispersion of small MA- and BA-ZrO2 clusters within PMMA homopolymers whereas the latter case was found to form large aggregates. The formation of the large aggregates is ascribed to reducing the unfavorable contacts between LOA-ZrO2 NPs and PMMA chains. Additionally, the ZrO2 NPs with surface grafted by a layer of LOA were found to preferentially segregate to the boundaries of cracks within the LOA-ZrO2/PMMA films. As a result, the conformational entropy loss associated with stretching of PMMA chains could be minimized. Moreover, LOA has the lowest surface energy. It is likely that LOA-ZrO2 nanoparticles preferentially aggregate to the free surface of poly (methyl methacrylate) thin films when thermal-annealing were implemented at a high temperature far above the glass transition temperature of PMMA. As a result, the thermal-annealed LOA-ZrO2/PMMA thin films revealed a morphology of dewetting. By contrast, the thin films of MA-ZrO2/PMMA and those of BA-ZrO2/PMMA still revealed homogeneous in thickness (i.e., fully wetting) on substrates.
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Yang, Wei-Chen, i 楊濰甄. "Morphological Evolution of Thermal Annealed Deuterated Polystyrene-block-Poly(methyl methacrylate) Thin Films on a UV-Treated Polystyrene Layer". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/jy5nvj.
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碩士國立中央大學
化學工程與材料工程學系
106
In this study, the structural evolution of deuterated polystyrene-block-poly (methyl methacrylate) (dPS-b-PMMA) thin films with thermal annealing of various durations on a layer of UV-irradiated polystyrene were studied by means of atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing incident small-angle X-ray scattering (GISAXS) and neutron reflectivity (NR). Upon exposure to UV light in a glove box and in air, the PS layer was cross-linked and neutralized. dPS-b-PMMA thin films supported on the cross-linked/neutralized PS layer were prepared by spin coating and then the specimens were isothermally annealed at 210280∘C under vacuum. We found that thermal annealing at a temperature below 270 oC would preferentially grew a wetting layer of dPS on top. The formation of the preferential wetting layer is due to the fact that the surface energy (dPS) of the dPS block was not equal to that (PMMA) of the PMMA block. In other words, below 270 oC, the free surface of the dPS-b-PMMA was not neutral. When annealed at 270 oC, dPS-b-PMMA would have a neutral free surface. Besides, we found that 270 oC-thermal annealing of a short period first led to the formation of perpendicular-oriented lamellae. Nevertheless, prolonged thermal annealing produced phase transitions from standing lamellae to vertical nanocylinders and finally to perforated-layer-like nanostructures. In this thesis, we would propose possible mechanisms about the morphology evolution.
Części książek na temat "Poly (methyl methacrylate) (PMMA) Thin Films"
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Ellison, E. H., i J. K. Thomas. "Photophysical Study of Thin Films of Polystyrene and Poly(methyl methacrylate)". W Multidimensional Spectroscopy of Polymers, 410–24. Washington, DC: American Chemical Society, 1995. http://dx.doi.org/10.1021/bk-1995-0598.ch024.
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Zhang, Q., C. Zheng, K. Sagoe-Crentsil i W. Duan. "Transfer and Substrate Effects on 2D Materials for Their Sensing and Energy Applications in Civil Engineering". W Lecture Notes in Civil Engineering, 409–19. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_42.
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AbstractThe recent emergence of two-dimensional (2D) materials such as graphene and transition metal dichalcogenides (TMDs) of the family (Mo, W)(S, Se)2 has attracted interest from a broad range of engineering applications, including advanced sensing and energy harvesting and conservation, because of their distinctive properties. However, it is critical important to achieve intact delamination and transfer of these atomically thin materials, as well as to understand the effects of the target substrates on their optical and electronic properties. Therefore, we developed and compared techniques for transferring as-grown WS2 crystals to arbitrary substrates. Polystyrene-assisted wet transfer can realize improved preservation of monolayer WS2 crystals than the commonly used poly(methyl methacrylate) (PMMA)-assisted wet transfer method, due to minimal chemical etching involved in the 2D material delamination process. The intercalation of alkali ions in the PMMA-based transfer method induces chemical doping over the transferred 2D crystals, leading to the formation of trions. Moreover, the edges of the crystals on hydrophilic substrates, such as sapphire or SiO2/Si, are subject to ambient water intercalation, which locally affects the photoluminescence behavior of the monolayer WS2 by doping and changing of the dielectric environment. This non-uniform optical behavior is absent when the crystal is transferred onto a hydrophobic substrate through which ambient water cannot penetrate. These results have important implications for the choice of target substrate and transfer method adopted for 2D TMD-based applications such as next-generation strain sensing, photodetectors, gas sensing, bio sensing, solar energy harvesting and radiative cooling in which uniform behavior of the channel material is required.
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Singh, Sudhanshu, i Umesh Kumar Dwivedi. "Fabrication and Morphological Characterization of Barium Titanate-Based Polymeric Nanocomposite Thin Films". W Multifunctional Nanocarriers for Contemporary Healthcare Applications, 50–59. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-4781-5.ch003.
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In this critical review chapter, the authors explain the development of composite films of Barium Titanate (BaTiO3) and Poly (methyl methacrylate) prepared by solution casting technique. Different weight percentage composition of BaTiO3 has been selected to find out the best optimization condition for further investigation and correlate the results. The structural properties have been carried out at room temperature using XRD. Efforts have been made to correlate the results with investigated XRD results of pure BaTiO3 and its composites as observed by other workers at room temperature. The flow of experimental work and microscopic images are explained.
Streszczenia konferencji na temat "Poly (methyl methacrylate) (PMMA) Thin Films"
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Kim, Ickchan, Mihai G. Burzo, Pavel L. Komarov i Peter E. Raad. "Thermal Conductivity Measurements of Ultra-Thin Amorphous Poly(Methyl Methacrylate) (PMMA) Films". W ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66507.
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As technology progresses towards smaller and higher density microelectronic devices, we are faced with working with atomic-scale dimensions that present us with challenges but also opportunities. Since mechanical and chemical properties of ultra-thin polymeric films can vary dramatically from their bulk, the thermophysical properties of thin films are also expected to vary. Ultra-thin poly(methyl methacrylate) (PMMA) films have been the focus of numerous investigations in recent years as a data storage medium. Employing Atomic Force Microscopy (AFM) technology, it is possible to store data bits by heating a target zone until it melts, which leaves a nano-dimple indentation in the PMMA polymer film. The AFM technology has great potential because it possesses considerable data density when compared to conventional magnetic data storage. Since the amount of heat that needs to be used to melt the nanoscale region of the polymer needs to be precisely controlled, knowing the thermophysical properties of such films is a critical factor in advancing this technology. It is known that heat carriers such as electrons and phonons in metallic and dielectric materials, respectively, are influenced by the “size effect” in the micro and nano-scale dimensions. Therefore, a goal for this investigation is to determine whether any dependence exists between the PMMA’s film thickness and its thermal conductivity. In this work we investigated whether a “scale effect” on intrinsic thermal conductivity actually exists for amorphous PMMA films with thicknesses ranging from 40 nm to 2 μm. The approach is based on the transient thermoreflectance (TTR) method, where the change in the surface temperature is measured by detecting the change in the reflectivity of the sample. The sample is heated by laser irradiation and probed using a continuous-wave laser that detects changes in the reflectivity of the heated material surface. The experimentally obtained transient temperature signature is then used to extract unknown values of thermal properties. Based on our previous experience with measuring a wide range of thin-film materials and the data available in the literature, we expected a lower thin-film thermal conductivity as compared to the bulk value. Surprisingly, the results show that the intrinsic thermal conductivity of layers thinner than 40 nm PMMA film deposited on native silicon oxide is about three times higher than the bulk PMMA value. A similar trend was observed for all ultra-thin (sub 100 nm) films.
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Pandey, Nisha, Arunendra Kumar Patel i Amrita Dwivedi. "Crystalline properties of ZnO doped poly (methyl methacrylate) PMMA thin films". W NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0061155.
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Ghebremichael, F., i R. J. Knize. "Linear Electro-Optic measurements of Dye-Doped Polymers". W Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.the.3.
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The basic Mach-Zehnder interferometer was modified for use in in-situ temperature dependent linear electro-optic (LEO) measurements of thin films of 4-dimethylamino-4'-nitrostilbene (DANS) doped into poly(methyl methacrylate) (PMMA). Optimum interferometer phase stability was possible because of an incorporated electronic feedback system. Film thickness variation was compensated for in order to obtain more accurate LEO coefficient measurements and thus the second order susceptibility. Moreover, both the α-relaxation associated with the glass transition, Tg, and β-relaxation associated with the secondary transition occurring below Tg of PMMA + 2%wt.DANS were obtained.
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Pandey, Nisha, Richa Khaling, Priyanka Verma, Poonam Pendke i Arunendra Patel. "Characterization of TiO2 doped poly (methyl methacrylate) PMMA thin films using XRD". W PROF. DINESH VARSHNEY MEMORIAL NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM 2018. Author(s), 2019. http://dx.doi.org/10.1063/1.5098705.
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Koike, Yasuhiro. "High Speed Polymer Optical Fiber and Related Photonics Polymer". W Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.thb.2.
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With the growing interest focused on the broadband network systems, optical fiber network for high speed telecommunication becomes more important in the premise network area. Silica base single mode fiber is an ideal medium for long distance communication because of its high transparency and high bandwidth, while its much low attenuation is minor advantage in the short distance network. As many data distributions and fiber connections are required in the premises wiring and LANs, low coupling and distribution losses must be maintained. Therefore, we have proposed a large-core, high-bandwidth graded-index polymer optical fiber (GI POF) for high speed data "transmission" medium, and we succeeded in several gigabit transmission in 100 m GI POF link. However, as the GI POF was composed of poly methyl methacrylate (PMMA), its high attenuation of transmission limited the GI POF link length to approximately 100 m. Recently we proposed the low-loss perfluorinated (PF) polymer base GI POF which enables more than 300-m transmission with maintaining high data rate.
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Abdeldayem, Hossin, Angela Shields, William K. Witherow, Benjamin G. Penn i Donald O. Frazier. "Benzil: a promising third order nonlinear organic material". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.mhh.7.
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Although benzil (C6H5CO)2 crystals have shown very low energy damage thresholds in producing second harmonic generation, thin films of benzil doped in Poly(methyl methacrylate) (PMMA) were found to be highly durable in withstanding high power lasers.
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Lizeng, Zhao, Lu Zhengzhong, Zhang Xiulang, Zhang Dongxiang, Mi Xin, Nie Yuxin, Wang Duoyuan i in. "Photon-Gated Photochemical Hole Burning in Zinc-Tetrabenzoporphyrin/Aromatic Cyanide System". W Persistent Spectral Hole Burning: Science and Applications. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/pshb.1991.the6.
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The group of Moerner,et al., first reported two-color hole-burning by donor-acceptor electron transfer for a derivative of zinc-tetrabenzoporphyrin as a donor with halomethane acceptors in a poly (methyl methacrylate) (PMMA) thin film [1]. Their results have opened up a new class of materials for photon-gating.
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Singh, Khushboo, Gauri Negi i G. C. Joshi. "Study of excitation energy transfer from Coumarin102(donor) to Coumarin6(acceptor) doped in poly-methyl methacrylate (PMMA) thin film". W PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON CONDENSED MATTER PHYSICS 2014 (ICCMP 2014). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4915471.
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Shen, Hui, i N. D. Gannon. "Analysis of the Mechanical Properties of Pristine and Thermally Aged PC/PMMA Micro and Nanolayered Films". W ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-37344.
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Microlayered polymer films are synthetic polymers with biomimicking layered structures which have been successfully commercialized. Nanolayered polymer films have been developed in recent years using advanced process technology. The innovative nanolayered polymer films have more complex hierarchical systems with truly biomimic nature. There are many potential applications for the nanolayered films such as gas barrier materials and spherical gradient refractive index lens. However, as polymers possess many properties that are different from metals and other traditional materials, the mechanical properties of the polymer films can vary widely depending on the material formulation, environmental temperature, and time. In this work, standard mechanical tests have been conducted to study the relationship between the mechanical properties and the layered structures. The impact of thermal aging on the mechanical behavior of the micro and nanolayered polymer films has also been investigated experimentally. The composition of the polymer films under study are 50vol% polycarbonate (PC) and 50vol% poly(methyl methacrylate) (PMMA). The layer thickness ranges from 31 nm to 32 μm and the film thickness 50.8 μm to 254 μm. These films were thermally aged at 115°C and 125°C in a constant temperature oven for up to four weeks. The mechanical properties, including the modulus of elasticity, tensile strength and ductility, have been tested on the pristine and thermally aged films. It has been observed that the mechanical properties of the films vary with the layered structure and film thickness. The thermal aging temperature and aging time have significant effects on the overall character of the stress-strain responses. Films with different thicknesses and layer formations respond to the thermal conditions differently.
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Majumder, Manisree, Aloke Kumar Chakraborty, Biswanath Mallik, M. R. Singh i R. H. Lipson. "Silver Nanoparticles Dispersed in Poly(methyl methacrylate) Thin Films: Spectroscopic and Electrical Properties". W TRANSPORT AND OPTICAL PROPERTIES OF NANOMATERIALS: Proceedings of the International Conference—ICTOPON-2009. AIP, 2009. http://dx.doi.org/10.1063/1.3183443.
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